nightcap Share definition Flag a drink (usually whisky/whiskey) taken at bedtime to aid a better sleep. i'm a bit agitated i think i'll have nightcap nightcap by Caleb Worsharski November 26, 2003 Words you can keep railfan mug chonk mug chud mug based mug 67 mug slime mug mogging mug chopped mug thot mug glazing mug huzz mug yams mug larp mug unc mug cracked mug simp mug baddie mug bop mug lolcow mug